SYSTEM_APPLE_II      = 0
SYSTEM_ATARI_2600    = 1
SYSTEM_ATARI_800     = 2
SYSTEM_COMMODORE_VIC = 3
SYSTEM_MICRO_BBC     = 4
SYSTEM_COMMODORE_64  = 5
SYSTEM_NES           = 6
SYSTEM_ATARI_5200    = 7
SYSTEM_ATARI_7800    = 8
SYSTEM_ATARI_LYNX    = 9
